CNC Machinery refers to machines and devices that are controlled by using programmed commands which are encoded on to a storage medium, and NC refers to the automation of machine tools that are operated by abstract commands programmed and encoded onto a storage medium.
Some of the early CNC machines were first built in the 1940s and 1950s, and these were based on the existing tools of that time. They were modified with electric motors which moved the controls to follow points that were fed into the system, on tape which was made from paper.
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These early NC systems were very quickly replaced by analogue and digital computers that have revolutionized the design process, and the modern computer numerical controlled (CNC) was created.
In todays CNC systems, end to end (start to finish) component design is very highly automated by using CAD/CAM programs. These programs create a computer file which is interpreted to extract the commands which are needed to operate a specific machine. It is then loaded into the CNC machine to enable production.
Very often a particular component may require a number of different processes which require a number of different tools drills, reaming or boring tools etc. However most modern machines will often combine many or multiple tools into a single cell. Other ways of completing this process may require a number of different machines which use an external controller and human or robotic operators which move the component around from machine to machine.